Such stairways are known in many type of constructions. They are in general adjusted individually to the respective type of aircraft and are structually integrated with same. Differently expressed, this means that known passenger planes in many cases have their own stairway or stairs which can be transferred only limitedly from one airplane to another. Since stairways of this construction are fixedly connected to the respective aircraft, they cannot be removed on short notice for use with other aircraft.
This has various disadvantages; in particular the lack of exchangeability is an increasing disadvantage because modern passenger aircraft are increasingly constructed to be readily and quickly convertible as desired from the passenger version to the freight version, and vice versa. In this connection it is of a special disadvantage if the stairway is fixed to the airplane.
A further disadvantage of the known airplane stairways consists in that these are at times constructed as under-floor stairs or form a single structural unit with the respective aircraft door. The first one of these two arrangements often represents an obstacle in the freight room which in almost all passenger craft is arranged below the cabin floor. Further, during installation of an under-floor stairway, in addition to extensive structural reinforcements, additional sealing measures must be taken. The second one of the above-mentioned arrangements, namely, having the steps integrated with the aircraft door, has the disadvantage that during an emergency evacuation that particular door cannot be used as an emergency exit.
The basic purpose of the invention is to avoid these disadvantages and to provide an autonomous airplane stairway which can be used as a basic unit for all passenger airplanes. Such purpose is substantially attained by causing, in the case of an airplane stairway of the type described above, the stairway section which is to be connected to the airplane to be secured for easy release on the cabin floor in the zone of the airplane entrance in such a manner that the stairway can be stored in folded condition within the airplane alongside the entrance thereof.
The inventive airplane stairway must thus be understood as an independent piece of standard equipment which can be used as a separate unit for each passenger airplane. Because of the seats which are to be secured on the cabin floor, the structure of the floor in the zone of the airplane door is already sufficiently reinforced that additional reinforcing measures for the stairway are generally not required. Furthermore the herein proposed equipment for an airplane stairway has the advantage that it needs to be carried along in the airplane only when airports without suitable ground entry and exit possibilities are involved.
In view of the free accessibility of the door during the flight, which is required for safety reasons, it is advantageous to arrange the proposed stairway laterally movable and lockable on tracks which extend transversely to the entry direction on the cabin floor. The tracks for the seats which are already present may be used within the scope of the invention as securement tracks. In view of the forces which are transmitted from the seat onto the aircraft structure, said tracks are already so constructed that they need not be additionally reinforced for receiving the inventive stairway instead of, for example, two to four seats. However, in such cases that the seat tracks cannot be used as tracks or as holding elements for the stairway of the invention, the invention provides further that between the stairway and the seat tracks suitable track pieces are arranged which can be secured on the seat tracks. It is in this connection understood that these track pieces are constructed in view of possible emergencies in such a manner that they can be tilted up laterally besides the door during the flight.
According to a further possibility of securing the stairway in the airplane which lies within the scope of the invention, it is provided that the stairway is secured through rotatably supported arms on the cabin floor, which make it possible to store the stairway package during flight beside the door so that same is freely accessible for emergency cases.
The stairway system of the invention has also advantages in that the airplane does not absolutely need to carry the stairway along in its freight version; it is sufficient to store at the airports in question some stairways according to the invention which, if needed, are available for the passenger versions. A further advantage of the proposed stairway is not the least in that through its use there will be on the whole substantial weight savings as compared with common stairways; compared with an under-floor stairway, it is for example over 30percent.
Further advantages and details of the airplane stairway of the invention can be taken from the drawings and the following description of the drawings.